Senate investigators spent months reviewing roughly 2,000 pages of federal records. What they found is damning. FDA and CDC officials under the Biden administration identified a significant stroke risk tied to Pfizer's COVID-19 bivalent booster in seniors - and never breathed a word to the public.
Sen. Ron Johnson (R-WI), chairman of the Senate's Permanent Subcommittee on Investigations, sent a formal letter to HHS Secretary Robert F. Kennedy Jr. laying out the evidence. He wasn't speculating. He was citing the government's own files.
"HHS records show that as early as October 2022, federal health officials identified a potential connection between the Pfizer-BioNTech COVID-19 bivalent booster and ischemic stroke for individuals over the age of 65," Johnson wrote.
An ischemic stroke means a blockage of blood to the brain. Between November 2022 and March 2023, seven separate analyses of incoming data flagged the same stroke signal — specifically in adults over 65. CDC data cited by Johnson shows 226 stroke cases reported between August 2022 and February 2023, with additional cases surfacing throughout 2023 and 2024.
Despite the risk, the Biden administration issued no formal warnings. No Health Alert Network message. No changes to booster recommendations for seniors. Nothing.
Instead, in February 2023, HHS quietly hired a private contractor, Lukos LLC, to conduct a deeper internal investigation, dubbed "The Stroke Project." Publicly, officials kept insisting the vaccines were safe.
"From the initial detection of the safety signal in late 2022 … health officials continued to say the vaccine was safe while simultaneously searching for evidence to support that assertion,” Johnson said.
It gets worse. Federal officials drafted a communications plan about the stroke risk that included a "Tough Questions and Answers" section prepared for President-ish Biden and his White House team. During final edits, the description of the stroke signal was quietly changed from "moderately elevated" to "slightly elevated." Who made that change? Nobody knows. The language softened, the edit went unattributed, and the public remained in the dark.
The pattern is consistent. Senate investigators previously established that Biden officials also downplayed the risk of vaccine-induced myocarditis and kept that from the public. This wasn't a one-time failure. It was a system.
Here's what makes this cover-up even more infuriating. The Biden administration showed it was more than willing to pull the plug on a vaccine when it wanted to.
In April 2021, officials paused the Johnson & Johnson (Janssen) vaccine due to blood clot concerns. The controversial move was pitched as proof of the administration’s commitment to safety. At the time of the pause, six cases of severe blood clots had been reported out of nearly 7 million doses administered. So when 226 stroke cases surfaced tied to Pfizer's bivalent booster in the most vulnerable seniors, the same administration did nothing. That double standard wasn't accidental; it was deliberate.
The fallout from that kind of institutional betrayal is hard to overstate. According to the Kaiser Family Foundation, fewer than half of all Americans now trust the CDC and FDA to operate free from political or special-interest influence.